This disclosure relates generally to an integral printing architecture containing at least a first marking engine and a second marking engine and more particularly concerns a media transport having an image quality sensing capability.
In a typical xerographic marking engine, such as a copier or printer, a photoconductive insulating member is charged to a uniform potential and thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member, which corresponds to the image areas contained within the document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing material. Generally, the developing material comprises toner particles adhering triboelectrically to carrier granules. The developed image is subsequently transferred to a print medium, such as a sheet of paper. The fusing of the toner onto paper is generally accomplished by applying heat to the toner with a heated roller and application of pressure. In multi-color printing, successive latent images corresponding to different colors are recorded on the photoconductive surface and developed with toner of a complementary color. The single color toner images are successively transferred to the copy paper to create a multi-layered toner image on the paper. The multi-layered toner image is permanently affixed to the copy paper in the fusing process.
A common trend in the office equipment market, particularly in relation to copiers and printers, is to organize a machine on a modular basis, wherein certain distinct subsystems of the machine are bundled together into modules which can be readily removed from the machine and replaced with new modules of the same type. A modular design facilitates servicing and repair, since a representative of the service provider simply removes the defective module. Actual repair of the module can take place off site, at the service provider's premises.
As demands for high speed copiers and printers have increased, the size and complexity of such systems have increased. As the size and complexity increases, the associated expense is often justified by only a small percentage of customers that offer extremely high volume printing. Recently, systems have been developed which include a plurality of marking engines. These systems enable high overall outputs to be achieved by printing portions of the same document on multiple printers. Such systems are commonly referred to as “tandem engine” printers, “parallel” printers, or “cluster printing” (in which an electronic print job may be split up for distributed higher productivity printing by different marking engines, such as separate printing of the color and monochrome pages). These systems have been designed primarily for the office market. A common trend in the office equipment field is to organize a printing system on a modular basis. Certain distinct subsystems of the machine are bundled together into modules which can be readily removed from the machine and replaced with new modules of the same type. A modular design facilitates a greater flexibility in the operation and maintenance of the machine. Such a system is disclosed in above-mentioned application Ser. No. 10/924,459.
Where two or more marking engines are employed in the generation of a document, the eye may detect inconsistencies between the images produced by different marking engines.